Catwalks, scaffolding, and other weight-bearing support structures are to a great extent formed from metal gratings or platforms, which comprise a perforated pattern of holes, such as circular holes, throughout their surface to lessen the weight of the structure, while not significantly decreasing the structure's ability to support a predetermined load. Some support structures are formed using cold-metal fabricating techniques, wherein the pattern of holes are formed in a given sequence, with regular spacing between the holes in the platform.
It is preferable to support such platforms from the side walls of buildings and other structures, so as to maintain the areas above and below each platform free of obstructions. This allows for the unimpeded movement of other mechanical devices in the area of the platform, such as overhead cranes, fork-lift trucks, and automatic inventory and storage facilities, by way of example. Previously, to provide proper support for platforms such as catwalks, vertical struts extending from the floor to the platform, or from the ceiling to the platform, have been used. Obviously, these vertical struts interfere with the freedom of movement of other devices being employed in the same building. To maximize the amount of usable open space available in a building of the type described, it is preferable to support catwalks and other platform structures from a vertical sidewall using a cantilever or right-angle bracket attached to the sidewall, with the platform rigidly fastened to the bracket.
When a person walks across a platform of the type described, lateral or horizontal forces are created between the platform and the elements used to fasten the platform to the supporting brackets. These horizontal forces are in addition to the vertical loads acting on the platform and its supporting brackets. For example, walking across the platform causes a tendency for the platform to shift laterally relative to its support elements.
Assuming the platform is fastened to a supporting bracket by a bolt extending through one of the holes in the platform, if the outer diameter of the bolt is less than the inner diameter of the hole in the platform through which the bolt extends, the lateral forces caused by walking across the platform result in lateral shifting between the platform, the bolt, and the support brackets. This eventually could lead to shearing of the bolt, weakening a portion of the platform itself, and ultimate failure of the connection between the platform and the support bracket. The possibility of such failure in prior platform devices is high, since it is not realistic or practical to assume that bolts will be found having the same diameter as the platform holes or apertures through which they extend.
Therefore, it is a primary object of the present invention to provide a fastening apparatus between a platform, such as a catwalk, and a support bracket which will hold the platform secure against the support bracket when the platform is subjected to lateral shifting forces.
A further object of the present invention is to provide a slotted bolt seat assembly providing a secure fastening system between a reticulated platform, a bracket supporting the platform, and a bolt tightly securing the bolt seat, the platform and the support bracket.
Another object of the present invention is to provide a slotted bolt seat which partially extends through an opening in the platform formed by removing material between two adjacent apertures in the reticulated platform, which opening also includes the two apertures, to form an elliptical or oblong aperture in which the bolt seat is lodged. The bolt seat reacts to lateral forces applied to the platform and holds the platform securely to the bracket.
Still another object of the present invention is to provide a slotted bolt seat assembly which is adapted to fit within a pre-fabricated mating slot in a platform to be supported from a bracket, whereby the pre-fabricated mating slot can be formed at substantially any location in the platform.
Yet another object of the present invention is to provide a method for securing an apertured platform structure to a support bracket by elongating and connecting two of the apertures in the platform to form an elongated or oblong aperture in the platform, inserting a bolt seat through the aperture, which bolt seat has a first portion seated flush against the upper surface of the platform and a second extensible portion which fits into and circumferentially engages the edges of the elongated aperture in the platform, inserting a bolt through the bolt seat, platform and bracket, and tightening a nut on the bolt to hold the bolt seat and platform securely against the support bracket. This method provides flexibility in the location where the bracket is attached to the platform.